A process of the above mentioned type and the corresponding arrangement are very often applied in the production of cups made of paper material. In the known process, the wall of a pot-shaped bottom is joined to a sleeve forming the interior in a liquid-tight manner along its entire height when the bottom skirt is formed. An inner tool used for pressing the sleeve and the bottom and also a corresponding outer tool both measure at least the height of the bottom skirt. The bottom skirt is as a result extremely stable and is very resistant to deforming.
In the case of cups made of paper material, the bottom skirt is a very important element of the cup. The bottom skirt is necessary for joining the sleeve and the bottom. At least two material layers are disposed in thickness direction on top of one another, namely the material of the bottom and the material of the interior-defining sleeve. The bottom is advantageously pot-shaped, the open side of said bottom facing away from the filling opening of the cup. The at least two material layers are advantageously arranged along the wall of the pot-shaped bottom. It can be additionally provided, for example, that the sleeve is folded inwards around the material of the bottom, and that the bottom skirt consists of three or more material layers. The material of the bottom is glued or sealed to the material of the sleeve in the area of the bottom skirt, in order that it is liquid-tight for at least a certain time.
The term “paper material”, from which the bottom and the sleeve are made, includes various material, which comprise at least one layer of paper, paperboard or cardboard. In addition the material can comprise one or more layers made of synthetics and/or aluminium. It can also be provided that the paper material is waxed or coated, in order to provide a resistance against the liquid with which the cup is subsequently filled. The paper material is advantageously coated at least on the side facing the interior with a thin synthetic layer, preferably made of polyethylene. In contrast to purely synthetic material, the formability and in particular the ductibility of such paper material is limited. In the case of too great a deformation, the paper material itself, or a provided coating, may tear, so that the liquid-tight properties are impaired. The bottom skirt is therefore an essential design feature in the case of cups made of paper material and cannot be omitted.
If types of bottom skirt are required which are formed in a subsequent procedural step after the liquid-tight attachment of bottom and sleeve is formed, then the design possibilities of these forms are limited, as the bottom skirt is very resistant to the forming process. The area of the bottom skirt is barely flexible and it can easily occur that the material at the bottom skirt tears when the bottom skirt has to be subsequently re-shaped. It may easily occur that the liquid-tight attachment between sleeve and bottom is damaged, so that the cup is no longer liquid-tight when subsequently used.
It is an object of the present invention to create a bottom skirt which ensures a liquid-tight connection between sleeve and bottom even in the case of subsequent re-shaping of the bottom skirt.
This object has been achieved in accordance with the present invention in that when the sleeve and the bottom are joined to one another, two height areas of the bottom skirt are provided whereby the wall of the pot-shaped bottom is only joined to the sleeve in a first height area, which is referred to as the “fixed area” of the bottom skirt, and whereby a second height area remains, in which the wall of the pot-shaped bottom is not attached to the sleeve, and is referred to as the “non-attached area” of the bottom skirt.
The produced cup comprises on its bottom skirt at least one non-attached area, in which the sleeve and the bottom are not attached to one another in a liquid-tight manner.
The object of the present invention relating to the process has been achieved in that at least the inner tool or the outer tool has a height which is less than the height of the bottom skirt.
The provision of a fixed area and at least one non-attached area has the advantage in that subsequent to the production of the liquid-tight attachment in the fixed area of the bottom skirt, the bottom skirt can be further formed in subsequent procedural steps, without the liquid-tight attachment in the fixed area being impaired. Re-shaping of the bottom skirt can for example serve to change the design of the cup or to integrate additional functions into the bottom skirt. The bottom skirt is advantageously re-shaped in subsequent procedural steps in the non-attached area of the bottom skirt in such a way that the fixed area remains unchanged in its form and the liquid-tight connection is not impaired.
The non-attached area is advantageously arranged on the side of the bottom skirt facing away from the interior, so that the wall in the area of the open end of the pot-shaped bottom is not joined to the sleeve.
When the sleeve is joined to the bottom, the wall of the pot-shaped bottom is advantageously pressed in the fixed area with the sleeve in such a way that a pressing force is generated between the inner tool and the outer tool. The height of the inner tool and/or the outer tool is less than the height of the bottom skirt, which ensures that a height area of the bottom skirt, which subsequently forms the non-attached area, is not covered over either by the inner tool or by the outer tool. In order that the attachment in the fixed area remains liquid-tight, it can be provided that a glue is applied to the material of the sleeve and/or the bottom in the area of the wall, before the two parts are joined together and pressed. If the sides of the sleeve and the bottom in contact with the interior are provided with a thermoplastic synthetic coating, the sleeve can also be sealed with the bottom in the fixed area, whereby the sleeve and/or the bottom are warmed up and are subsequently pressed to one another only in the fixed area. Warming up to the point of melting of the synthetic coating can take place by means of a heated inner tool and/or an outer tool when the parts are pressed to one another, or by means of blowing hot air. The warming up extends hereby at least to the fixed area of the bottom skirt. The sleeve is advantageously warmed up in the area of the bottom skirt by means of blowing with hot air before the pot-shaped bottom is applied. After the bottom is applied to the sleeve, the material layers are pressed to one another in the fixed area, so that a liquid-tight sealing forms in this area.
In an advantageous embodiment of the present invention it can be provided that the bottom skirt is widened in the non-attached area at least in an area along the periphery. The lower edge of the widening can form a standing surface for the cup. The standing surface is increased by the widening, so that the cup cannot tip over so easily. When the bottom skirt is widened in the non-attached area, the material layers of the sleeve and of the bottom can slide against one another, as they are not attached to one another. The risk that the paper material, or a coating applied thereto, tears during forming of the widening is hereby greatly reduced. For the purposes of widening the bottom skirt, the arrangement for producing the cup can comprise at least one widening tool in a working station, which is arranged downstream of the first working station with the inner tool and the outer tool for forming the bottom skirt, which widening tool can be placed to the non-attached area. In addition a supporting tool can be provided, which can be placed to the fixed area of the bottom skirt during widening, and which prevents distortion in the shape. It can be provided that the bottom skirt is in addition warmed up in the non-attached area either before or during widening. If the widening at the bottom skirt is to be very stable, it can be provided in addition that the wall of the bottom is joined with the sleeve during or after the widening process, for example in that the non-attached area is warmed up to a temperature sufficient for sealing.
In a further advantageous embodiment, the widening at the bottom skirt forms a means for holding another cup of the same type. It can be hereby provided that a first holding means is formed on the sleeve defining the interior, which first holding means can act together with a second holding means on the bottom skirt. Furthermore, it can be advantageous that an outer sleeve is arranged to the cup, which serves to improve the insulating effect. The form of the outer sleeve is optional and is applied advantageously to the cup before the widening is formed in the non-attached area of the bottom skirt.